First, we must come to peace with what makes a strong rotation in 2019.

In the traditional sense of who has the best five-starter group, I think the Indians, Rockies and Mets grade out best. But Cleveland and Colorado project to iffy bullpens when even the heaviest-workload rotations are going to need scads of relief help.

The Mets have depth concerns beyond their top five. Derek Carty, who does fantasy baseball for ESPN, uses a system that shows the Dodgers have nine potential starters who are better than the best starter on nine other teams. Yet, once Los Angeles traded Alex Wood to Cincinnati, it was left with zero starters who even qualified for the ERA title last season.

And the Rays distorted the concept of a standard rotation by more than any other team using “openers” last season. They used 17 different starters — the most in 22 years — yet thrived in suffocating offenses. Tampa Bay also produced the first ever AL Cy Young-winning starter in an uninterrupted season with fewer than 200 innings (Blake Snell at 180 ²/₃ ).

This is the new world. A rotation can no longer be viewed as a stand-alone item. Instead, it falls under a run-prevention umbrella along with relievers, pitching depth and defense — and how all those pieces fit together.

“But there still is a tremendous value in having quality starting pitching,” Aaron Boone said Thursday, shortly after this pitchers and catchers had officially taken the field for the first time. “Those innings are humongous.”

So back to this: Do the Yankees have good rotation?

The answer becomes a definitive, yes, if their bullpen is as good as anticipated and James Paxton is ready to take another positive step in quality and durability.

Brian Cashman insists he tries to construct a rotation by “bringing in as many 200-inning guys who will get Cy Young votes and allow [pitching coach] Larry [Rothschild] to deploy his bullpen as he desires.”

However, the Yankees GM also said he has invested in a deep bullpen because, yes, that is a reality of how the game is played these days, but also the reality of what complements this Yankee rotation.

None of the Yankee projected starting five reached 200 innings last year — the leaders were Luis Severino (191 ¹/₃) and J.A. Happ (177 ²/₃, mostly with the Blue Jays). And three did not even qualify for the ERA title (minimum 162 innings). Those three, though, came in just beneath: Paxton (160 ¹/₃), Masahiro Tanaka (156) and CC Sabathia (153). But all five had ERAs at least 8 percent better than MLB average (factoring in park and league). Thus, the Yanks have the only projected 2019 rotation with five members who each exceeded 150 innings with better than a league average ERA.

So, there is quality here, but quality limited last year by either a) short-term injury and/or b) strategy to reduce innings within games. That kind of rotation would benefit from a powerhouse bullpen so that starters did not have to be pushed in individual starts and to better protect a fill-in starter such as Domingo German or Jonathan Loaisiga.

The Yankees have six relievers on their current roster (Dellin Betances, Zack Britton, Aroldis Chapman, Chad Green, Jonathan Holder and Adam Ottavino) who last year were among the top 63 in OPS-plus against — or one more than the rest of the AL East combined.

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Still, to best mobilize the relievers and avoid overexposure, Boone appreciates, “the number may have moved [downward] for what you expect [in innings], but you still better get innings from your starters to avoid blowing out your pen. You may not expect CC to give those mammoth innings now, so it is important we get them from Sevy and Paxton.”

Severino (384 ²/₃) has thrown the second-most innings in the majors the last two years — and the team is confident experience will permit him to shuck issues with tipping and fatigue that arose, particularly late last season. Paxton has never even qualified for the ERA title. But the Yanks believe they are getting a starter with ace-level stuff at the right time. Paxton expects more thoughtful workouts and diets will better fortify his body to endure 30 starts.

“My goal is to get to the 200-inning range,” Paxton said. “I understand the bullpening and leverage, but I wonder if those relievers who are being pushed to constant two- and three-inning stints will run out of gas. I think it is still up to starters to provide innings.”

In the Yankees’ best-case scenario, Paxton gives those innings in tandem with Severino atop the rotation, with Tanaka, Happ and Sabathia providing less bulk, but still quality, supported by that deep, talented pen. That is the formula to how the Yankees get to a yes to the question: Do they have a strong 2019 rotation?